How humans evolved from single-cell organisms

Genetic analysis indicates that every organism on Earth evolved from a single cell

LUCA—the last universal common ancestor—lived about 4.2 billion years ago and likely obtained energy through the conversion of carbon dioxide and hydrogen gas consumed from atmospheric gases at the ocean's surface or hydrothermal vents—openings on the seafloor where fluid warmed and enriched with minerals by Earth's interior is expelled.

Human origins 101

Learn about the over 20 early human species that belong in our family tree and how the natural selection of certain physical and behavioral traits defined what it means to be human.

The evolution of the human brain

The human brain, in all its staggering complexity, is the product of millions of years of evolution. Read on to find out about brain size and intelligence, language and brain development, and more.

The messy story of humanity's genealogical past

For decades, scientists viewed the human fossil record and concluded Neanderthals, an early hominin, came before homo sapiens, or modern humans. The story became more complicated as technology advanced and ancient DNA samples were analyzed. This video breaks down the evidence, concluding the development of humanity was a lot messier than previously believed.

Humans have existed for just 0.004% of Earth’s history

Born from the remains of the molecular cloud that birthed the sun, Earth experienced planetary-scale collisions, asteroid impacts, and lava seas. Life became possible after the planet cooled and formed a thin crust, atmosphere, and oceans.

Why humans survived and smarter species did not

This interview with Joseph Henrich, a renowned professor of human evolutionary biology, unpacks human history. Henrich shares interesting information about why humans succeeded as a species (the answer isn't IQ), how cultural evolution works, why the human brain is shrinking, and how the Catholic Church played a role in the Industrial Revolution. Listen and watch for a deep dive into human evolution.

Even in recent history, adaptations to the environment drove human evolution

Through genetics, environmental pressures, and cultural influences, humans have evolved to tolerate lactose, develop varying skin pigmentation, and acquire genetic resistance to diseases like bubonic plague. The metabolic and digestive systems of Indigenous peoples have adapted to their diet, which is influenced by the availability of food and water.

Studies estimating the number of years between human generations suggest there have been approximately 10,000 to 12,000 generations of humans.

Research has found that the length of human generations has varied throughout the 300,000 years that Homo sapiens have been around, ranging from about 25 to 30 years. These values come from analyzing genetic mutations, since the blend of them passed onto children changes as parents age.

The history of the gene: an interactive timeline

Humans didn’t need modern technology to figure out that kids tend to look like their parents. But what did humans believe about genetics before we knew about DNA or cells in general? Explore this interactive timeline to see how philosophers and scientists throughout the ages tried to explain how traits are passed from generation to generation.

Blood evolved many times over hundreds of millions of years

The earliest evidence of a blood-like substance comes from ancient arthropods, which appear to have had copper-based blood. In the 500 million years since then, some creatures have grown to rely on other variants, such as humanity's iron-based blood.

Tracing the evolution of mobile phones

The first cell phone was created in 1973, with a 2.4-pound handset and a battery life of about 30 minutes. Since then, pretty much everything about it has drastically changed, with more than 5 billion cellphone users across the globe (that's more than half of the world population). Learn about the evolution of the mobile phone and where the technology may go in the future with this four minute video.

Why humans evolved single-child pregnancies

While birthing twins has been a rare occurrence for humans, research suggests that twins were actually the norm much further back in primate evolution. It’s proposed that single-childbearing turned out to be critical for the evolution of larger babies with larger heads. Discover more about the shift that gives insight into primate evolution.

The lifestyles of early humans

For 2.5 million years, humans lived on Earth without leaving a written record of their lives—but they left behind other kinds of remains and artifacts.

Explore the independent lines of evidence behind the theory of evolution

Gradual changes in organisms have been directly observed through artificial selection—humans purposely selecting organisms to breed to pass on specific traits—and in organisms with short lifespans, such as insects and microbes. Analyses of DNA and anatomical structures across different species, as well as fossil records, also reveal ancient shared ancestry consistent with natural selection.

Mapping how human population has grown throughout history

It took 200,000 years for our human population to reach 1 billion—and only 200 years to reach 7 billion. When will our global population peak? And how can we minimize our impact on Earth’s resources, even as we approach 11 billion?

An interactive timeline of history, from beginning to middle

The history of humanity is a long, winding road, and the history of everything else is even more complex and interwoven. This interactive timeline takes users through the history of the world and includes links to related videos, blurbs, and events. Each event in history is represented by a dot, providing users with a glittering horizon filled with moments of intrigue and impact.

Bees evolved from meat-eating wasps that became vegetarian

After flowering plants first appeared approximately 140 million years ago, some wasp diets would have changed as they consumed pollen-coated insects that would visit these plants. Bees that branched from these wasp species also developed long tongues to slurp nectar and ultraviolet vision to identify flower patterns unseen by humans.

The history of China: a timeline

How long has China existed, and how and when did it evolve into its form? Explore the journey of China from empire to republic (to a republic, again) in this timeline. Archaeological evidence suggests the earliest Chinese dynasty formed at about...

The oldest DNA recovered so far is 2 million years old

The oldest DNA recovered so far is about 2 million years old and has given scientists an unadulterated peek into ancient history. This nine-minute video explores the findings and implications of the DNA, which was pulled from frozen soil in...

The tongue evolved in animals roughly 350 million years ago

Creatures like fish rely on suction to consume food, flexing their gills to create water currents that vacuum up their meals. The evolution of the tongue enabled vertebrates to completely cut ties with the sea, moving onto land where they could sample new foods and ways to eat them.

'The urge to explore has propelled evolution since the first water creatures reconnoitered the land. Like all living systems, cultures cannot remain static; they evolve or decline. They explore or expire.'

- Astronaut Buzz Aldrin (1930-present)

How flowering plants took over the world

Flowering plants are relatively young in the evolutionary scheme of things, only arriving after the dinosaurs had already been wiped out. Their evolution has long puzzled scientists, but recent research indicates their success is due to smaller,...

Humans won't develop more than 5 fingers because it would impact too many body parts

All modern animals have five or fewer digits on each of their limbs. Roughly 348 million years ago, at least two species had eight: the Ichthyostega and the Acanthostega. According to Dollo's law, complex evolved features are very unlikely to recur in evolution. Researchers believe humans won't develop more than five digits because it would impact other body parts too much.

Scientists first observed a sperm and an egg uniting in 1876

Throughout human history, scholars and researchers have speculated on the origin of human reproduction. It wasn't until the late-19th century that the physical process of egg fertilization via sperm cells was observed (in sea urchins), forming the basis for modern fertility research.

More than 100 types of beer are produced around the world

Beer dates back to ancient times, and since then, the fermented drink has taken on many different styles around the globe, depending on the grain and ingredients used. See how pilsners, IPAs, Sours, and other types evolved from the drink's early history.

See how each of the more than two million known species relates to each other—and to common ancestors—in this zoomable tree of life.

The first line of 'immortal' human cells, which can divide indefinitely and are used in scientific research, was nonconsensually taken from a Black woman.

After NASA's Voyager 1 captured Earth as a single pixel as it left the solar system in 1990, astronomer Carl Sagan used the image to reflect on humanity's fragility and the responsibility to protect 'the only world we've ever known.'

Watch how viruses like Ebola can spill over from animals to humans—and vice-versa.

Before humans, the Soviet Union and the United States sent animals—including apes, dogs, and cats—to space during the Space Race.

Budweiser stores yeast derived from the original 1800s strain in a secret bunker, which only the Head of Yeast Management can access—not even the CEO

Scientists can determine Earth's past climate conditions by analyzing air trapped in microscopic bubbles within ice cores—columns of compressed snow layers that build up over hundreds of thousands of years.

Learn more about the history of fireworks, which dates back to an accidental invention during an alchemist's quest for information about immortality.

The syncytiotrophoblast is the outer layer of the placenta and the largest human cell, spanning an area about twice that of a king-sized bedsheet.

Crows are believed to have intelligence on par with a seven-year-old child and demonstrate complex behaviors, from problem-solving with tools to recognizing human faces.

Hear about the 250-year history of the United States Postal Service, complete with some of its strangest deliveries, important innovations, and the figures that made it an American institution.

In 1963, a basement renovation in Turkey revealed a passageway to a hidden, multilevel underground city that once housed as many as 20,000 people

Trace how the Bill of Rights, inspired by centuries of political theory, took shape between 1774 and 1789.

Watch how algorithms can be designed to train themselves and self-improve without human input, to the point where the optimized code is too complex for programmers to understand.

The American cockroach is actually from Africa, an apparent hitchhiker aboard ships carrying enslaved people, with evidence suggesting the bug may have arrived in the New World as early as the 1600s.

Apeirophobia is an overwhelming fear of living forever, perhaps stemming from the brain's inability to conceptualize an infinite life.

Massive blooms of microscopic plankton called dinoflagellates produce the neon blue light seen in glowing tides.

The animatronic shark from Steven Spielberg's 'Jaws,' the first modern blockbuster, was a complex underwater apparatus called 'Bruce.'

Planarian flatworms are small, aquatic worms with exceptional regenerative capabilities. When cut, the worms can regenerate multiple bodies in a matter of weeks.

While the first exchange-traded fund (a 'basket' of different assets that can be bought and sold on a stock exchange) in the US only launched in 1993, the global ETF market has grown to more than $10T in the short time since.

US housing costs have risen by roughly 175% between 1991 and 2026—but a growing number of Gen Zers are becoming homeowners anyway. In 2025, 4% of homebuyers were Gen Z, up from 3% the year before.

Studies suggest when you sleep is as important as how much you get, and syncing with your circadian rhythms may lead to less fatigue and improved long-term health outcomes

SpongeBob exemplifies Aristotle's philosophy for living well because he understands that happiness doesn't come from external factors like money, recognition, or power.

Take a 3D tour of the Hajj, Islam's annual pilgrimage to Mecca, undertaken by over 1.5 million Muslims.

The word 'jazz' evolved from 'jasm,' 19th-century American slang for 'energy'